Signaling system



H. H. scHNEcKLcTl-l March 20, 1945.

SIGNALING SYSTEM Filed July s, 194s 2 sheets-sheet 1 H. H. SCHNECKLOTH SIGNALING SYSTEM `Mmh 2o, 1945.

2 SheevtS-Sheet 2 Filed July 3, 1945 ATTORNEY Patented Mar. 20, 1 945 i isra'rss PATENT nourrice 2.372.022, srGNAmNG SYSTEM HarryHsSehmeckloth; Eorcs-tfHiSi Y.,.assi gnorto.V Bell .Laboratories Incorporated-,.

erk, N. Y.av;corporation..of. New York momma. (orne-am This invention vrelates to. telephone systems and particularly to systems comprising an rm- 'attended' automatic ofiice..

`Objects of the invention arext'he. improvement tion of .a call over said particular line, theparticular. `tone .thus transmitted vbeing indicativeof the. character of the troubley condition then exist;- .ing'in the unattendedoce.. v According. toa rurlther feature of the inrentior-i` means are. pro vided in the unattended office `for. disconnecting I .the trouble. tone. .from .the lui-neer. trunk respon- .sire to.-.seizure of thel-ine in. the unattended @dice 4for use on. a regular call.

These .andother ieatures or the will `lector-ther explained'hy considering theesystemsi-n which: theinvention isremlaoclied,l one such'. `system y-berog-shcmm: the drawings whichare a. parteci ,thisspecicatiom .Theinventiom is noi:` limited,

drawings or to a `:system comprising. switches 'of ,any `parti-cular type; `lout' vis generally-applicable vtio-any automatic'switchingusystem comprisingsan l unattended central oficei.

Reierring, .to the drawings, Fig, L represents y a part kof an unattended aisltomatic:l ltelephone @meer comprising a. subscribersstation Asazndline y Lt, fa .line-finder a .first-:selector Si,Y :an incoming .-selector`IS,..fa/ :connector CL. -a called 'simreribers liras-.i321 andstaitiorr'lzand a; circuit TEGI: connected to-fa setof tenninalsm the bank of. the selector; Si;

12' shows in i-the imattendedf om'ce,

` :alarm equipmentromprising an: :auxiliary trunk A'IECEI connecting: 'the trunk circuit TGI :of Eig. .1. to an 'outgoing trunk .'II extending toa master oiiioe; Fig. 2; further shows, inthe' imastervofice.. a; trunk .circuit TG2 terminating #thee-dirimir andan; operatofszposition) comprismcfthefcord-SDL 'The linesndenselector-:andrconnector switches comoA Ice or the. meltknown ftwo-motion step-'bzwL plurality of tone sources responsive to the initia- .however,. to the particular system. disclosed in the step type. Reference maybe-ifradto'liutomatic Telephony by Smith and z'(J'a'rrrpbell, second edition, 'pages =53 to 65' fora descriptionyof the structure or suchv switches and 'their operation 'when used as selectors 4and connectors. Reference may be liad to jthe patent to R. Stokeiy 799,654', April' 1'T, 1931, and' thek patent to' L. Urmond. 2210;'068, August 6, 1940;, 'for a Idescription oT the operation" of twoenrotion Istep-byistep yswitches''vvi'ien 4'used as "linefilnders' The subscribers .stations A and B an'd the other 'stations of? unattended oiice are of 'the type `usually provided' onlinesterminating'iin common "battery .centrale oflicesj;"`and veach Kincludes a. Adiail for other impulse senderv forl controlling the opera- .tion ofthe automatic.switrh'eszthrough which desired vconnections are established'. 'The line finder "LFZ selector S.I,..i`ncornin'g selector 'IS and connector CII are each represented by Ia lset of 'brushes .and oneor two :sets of' terminals oi. the associated tenninal'hank all other apparatus being, omitted.

'Each of .the -lnelnders such asfliFis 'individually I associated with ayirst, selector such asA S1; and

.these selectors may have direct .access to .groups 'ofsoutgohg trunks.- and. connector switches, as

.shown .in the. drawings.. If, however, the number of subscribers .inthe oflce .makes necessary the .provision or one .or more additonalstages of` se.- lectony .intermediate .selectors Will/.be provided.

A The .trunk Tlf, which represents a .group 'ofy trio-way trunksbetween. theuna-ttended. omceand ani operator's. positionin themaster office, is

y vrrorrxrallly .connected .in the, `unattended foilice to the twee-way .trunk circuitfllCl. thetattended omas. ther trunk '.'II terminates. in a. twoeway trunk The trunk vcircuits ICL and TG2 are-similar .to trunk. circuits TCI and TCB disclosed in the patent.- to Walters 12,252,595,

".-granted. November 11,' 19.41-. .Reference may he .had .toit-1re. patent .to King.et...a1..2.2o,7s5, granted July 23,..l.940 for. a. complete disclosure. or the .jcerdand operatorie position. circuits.. Only .so much of. thetrunk circuits 'IGtand 'RC2 is shown :as is necessary towaaliord`r acompletefdisolosurepf applicants invention.

auxiliary trunk circuit .ATCiI-- isf associated 'with `a: particular one cfg the trunks in. the group:lietvveenthe unattended and. master offices to enabie. the; transmission of trouhlefsignals to tlre ima-ster ofce.. .A similar. trunk` circuiti may he. 'associatedzzwith .anotherP oixtheztrunks in vthis' group :to 'ff-provide vfor-.the transmissonor trouble tonesxtothenmasterfoince im :case therst trunk 1is-d-isaalcied.or temnorariwremcved; The trunk circuit ATCI enables the transmission of maintenance alarms over the trunk circuit TI to the master oice on trouble checking calls from the master office and the removal of the tone if a regular cell is being established. This trunk circuit comprises a line relay 1I, a relay 69 for transferring the conductors of trunk TI from relay 62 of trunk circuit TCI to relay 7|, aslow-to-release relay '12, `slush-reve relayY 66, and control relays 61 andlB. r

The alarm equipment further comprises a plurality of alarm relays BI, 82, 831 and 84 and a cor- Y responding plurality of tone sources BI, 92, 93 and 94. Each of relays 8l, 82, 83 and 84 is Voperatively responsive to the occurrence of a diierent type or severity of trouble in vthe unattendedrelay B I, and upper winding of relay 62 to ground. Relay 62 is not operated by the current in this circuit because it is marginal and the upper winding of relay IIlI is a high resistance winding; and relay IIlI is not operated because it is polarized and the current is in the non-operative direction. The aforementioned operation of relay 6I interchanges the connections between the windings of marginal relay 62 and: conductors ,63 and 64, thereby-to reverse the direction-of the current over trunk TI to effect the operation of polarized relay IUI of trunk circuit TG2 in the master oice.

. Theconnection of ground to conductor 53 also oilce, the operation of any of lthese relays being'A effective to operate relay 69, providing the trunk' TI is not then engaged on a regular call, tompre-V pare for the connection of the associated ton source to the trunk TI.` v

Assume first that no trouble condition exists in the unattended oilce when va call is initiated at station A. A line finder LFis operated to connect the line LI toa i'lrst selector SI; and, when the calling subscriber dials the first digit of a called subscribers number or special service code, the selector SI is selectively operated to select the corresponding level of the terminal bank'and to select therein the first idle set of terminals, which terminals are connected to a connector CI in the case of a local call or to a trunk circuit associated with a trunk to the master oiiice. If the call is a local call, the dialing of the succeeding digits of the called subscribers number effects the cornpletion of the call in usualand Well-known manner. If the calll is other than a local call and assuming the trunk circuit TCI to be associated with the selected set of terminals in the level giving access to the group oftrunks to the master cnice, relay 56 is operated ina circuit traced from Ybattery through the lower winding of relay 56, inner lower back contact of relay 58, lower left winding of repeating coil 60, another back contact ofV relay 58, conductor 52, terminal of terminal set 50 which is engaged by brush 22 c f selector SI, brushV I2' and engaged termin'alof line finder LF, over the conductors ot line LI and through the telephone at the callingfstation A, through the terminal engaged by brush ll of line nnder LF, brush 2| andengaged terminal of selector SI, conductor l, outer upper ,backl contact of vrelay 58, upper left winding of repeating coil 68, inner upper back contact of relay 58, and

upper winding of relay 56, to ground. The oper- .A I

ation of relay`56 closes a circuit for operating the Vthe lower winding of relay 62, lower back contact of relay 6I, lower right winding of repeating coil 68, conductor 64, lower back contact of relay 69, lower conductor of trunk TI, lower left winding of repeating coil |60, both windings of relay IUI, upper left winding of're'peating coil |00; upper conductorl of trunk- TI, upper back ycontact of relay 69, conductor 63, upper' right winding of repeating coil 66, inner upper back contact of completes a circuit, through conductor and the winding of relay 66 to battery at a back con- -tact of relay 68,' for operating relay 66 to prevent the operation of relay 69 in case one of relays 8l, 82, 83 and 84 should operate before the call from station A is terminated. The operation of relay I 0I closes a circuit for operating relay I2; and the operation of relay |02 closes a circuit for lighting the answering lamp AL associated with the jack J2. When an operator inserts the plug P `of a cord CDI in jack J2 to answer the call, relay |63 is operated, in the manner described in the aforementioned patent to Walters, to release relay I02 and extinguish lamp AL. The operation o relay |03 also short-circuits the upper, high resistance winding of relay IGI thereby to increase the current in the circuit over trunk TI to operate marginal relay 62. The operation of relay 62 closes a circuit, including the upper front contact of relay 54, for operating relay 55; Vand the operation of relay 55 closes a circuit for holding relay 54 operated independent of the continued operation of relay 56. When the calling subscriber releases the connection by restoring the telephone to normal, relay 56 releases. The release of relay 56 causes the release of relay 6I; but relay 54 remains operated until relay 55 releases. The release of relay 6I, reverses the current over conductors 63 and 64 and trunk Tl torelease polarized relay I 0I of trunk circuit TG2, whereby a cord supervisory lamp (not shown) is energized as described in the aforementioned King et al. patent. vWhen the plug P is removed from jack J2, the release of relay |03 opens the short-circuit across the upper winding of relay IUI thereby causing the release of `marginal relay 62 of trunk circuit TCI.- The release of relay 62 causes the successive release oi v'relays 55 and 54. The release of relay 54 disconnects the busy and holding ground potential from 'conductor 53 thereby causing the release of relay 66 `of trunk circuit ATCl and the return of selector SI and line nder LF to normal in usual and Well-known manner.

If an operator in the master cnice inserts the plug P 'of a cord CDl in jack J2 to initiate a call over trunk TI to the unattended oiiice, relay I0 3 is operated in the manner described in the aforementioned patent to Walters. The operation of relay Ill3 short-circuits the upper winding of relay IDI; and, if relay 65 of the auxiliary trunk circuit ATCI is not operated, the increase in current through the conductors of trunk TI effects the operation of marginal relay 62 of trunk circuit TCI. The operation of relay 62 closes a cir- ;cui; including back contacts of relays 54 and 6I vfor 4operating relay 58. The operation of relay '-58 connects the winding of polarized relay 51 in series with the left windings of repeating coil 60 across conductors 4I and .42 of incoming selec- .tor ISthereby to prepare this selector for 1re- -sponse to dial impulse transmitted over trunk and may, of course, make regular calls. If a trouble condition exists at a `time that the subscriber desires to make a regular call, the trouble tone may be disconnected by the dialing of a digit.

Whatis claimed is:

l. In a central oice of a telephone system, lines including subscribers lines, means responsive to the initiation of a -call at the distant end of a particular one of said lines while a trouble condition exists in said o'ce for transmitting over said line a distinctive tone to indicate the existence of said trouble condition.

2. In a central ofce of a telephone system, lines including subscribers lines,means responsive to the initiation of a call at the 'distant end of a particular one of said lineswhile a trouble condition exists in said oilce for transmitting over said line a distinctive tone to indicate the existence of said trouble condition, and means controlled over said line for terminating the transmission of said tone over said line.

3. In a central oice of a telephone system, lines including subscribers lines, subscriber controled switching means for establishing connections between calling and called lines, means including means normally responsive to the initiation of a call at the distant end of a particular one of said lines for connecting said one line to said switching means, means responsive to the initiation of a call at the distant end of said one line while a trouble condition exists in said omce for transmitting over said one line a distinctive tone to indicate the existence and character of the trouble condition, and means controlled over said one line for ending the transmisison ofsaid tone over said line.

4. In a central oflice of a telephone system, lines including subscribers lines, subscriber con.- trolled switching means for establishing connections between calling and called lines, means including call responsive means normally connected to a particular one of said lines for connecting said one line to said switchingmeans upon initiation of a call at the distant end of said one line, other call responsive means for responding to the initiation of a call at the distant end of said one line, means responsive to a trouble conditionin said oil'ice :for connecting said other call responsive means to said line in place of said normally connected call responsive means, and means rendered effective by the operation of said other call responsive means for transmitting over said line a distinctive tone indicative of the trouble condition which exists in said oiiice.

5. In a central oilice of a telephone system, lines including subscribers lines, subscriber controled switching means for establishing connections between calling and called lines, means including call responsive means normally connected to a particular one of said lines for connectiIii-r said one line to said switching means upon initiation of a call at the distant end of said one line, other call responsive means for responding to the initiation of a call at the distant end of said one line, means responsive to a trouble con- 6.' In a central office of a telephone system, lines including subscribers lines, subscriber controlled switching means for establishing connections between calling and called lines, means including call responsive means normally connected to a particular one of said lines for connecting said one line to said switching means upon initiation of a call over said one line, other call responsive means for responding to the initiation of a call over said one line, means responsive to a trouble condition in said otlice for connecting said other cally responsive means to said line in place of said normally connected call responsive means, means rendered effective by the operation of said other `call responsive means for transmitting over said line a distinctive tone indicative of the trouble condition which existsin said oce, and means controlled over said one line for effecting the reconnection of said one line to said normally responsive means. i

7. In a central oftlce of a telephone system,'lines including subscribers lines, subscriber controlled switching means for establishing connections be tween calling and called lines, means including call responsive means normally connected to a particular one of said lines for connecting said one line to said switching means upon initiation of a call over said one line, other call responsive means for responding to the initiation of a call over said one line, means responsive to a trouble condition in said oifice for connecting said other call 'responsive means to said line in place of said normally connected call responsivemeans, and means rendered effective by the operation of said other call responsive means for transmitting over said line a distinctive tone indicative of the trouble condition which exists in said oice, and means controlled over said one line for disconnecting said one line from said other means to end the transmission of said tone and for connecting said one line to said normally responsive means to eiect the connection of said one line to said switching means.

8. In a central oiiice of a telephone system, lines including subscribers lines, subscriber controlled switching means for establishing connections between calling and called lines, a plurality of tone sources each producing a tone of a different character and corresponding to a different trouble condition in said oilce, means including means individual to one of said lines rendered eiTective by the occurrence of trouble in said oiiice and the initiation of a call at the distant end of said one line for connecting to said one line that one of said tone sources which identifies the trouble then existing in said oiiice, and means controlled over said one line for disconnecting said tone source from said line.

9. In a central oce of a telephone system, lines including subscribers lines, subscriber controlled switching means for establishing connections between calling and called lines, means including call responsive means individual to one of said lines and normally connected thereto for connecting said line to said switching means responsive to the initiation of a call over said one line. a plurality of troubletone sources, the tone from each of said sources being indicative of a different trouble condition in said office, a plurality of relays, one for each of said tone sources, means responsive to a trouble condition' for operating the relay which is associated with the tone source which corresponds to the character of the trouble, other call responsive means individual to said one line, means responsive to the operation of any said other relay to said one line in place ofthe normally connected relay, means in said unattended ofce rendered effective by the operation of said other relay for transmitting a. tone signal over said one line to said attended oflice to indicate the character of the trouble condition then existing in said unattended oiilce, and means controlled over said vone line for effecting the disconnection of said one line from said otherrelay and the reconnection of said one line to said normally connected relay.

1'7. In a telephone system, an unattended ofnce comprising subscribers lines, an attended ofce, trunk lines between said oiilces, automatic switching means in said unattended voffice for completing connections between calling and called lines, a particular one of said trunk lines being used for the transmission of trouble signals from said unattended office to said attended ofi-ice, means in said unattended oilice for seizing any one of said trunk lines on a call Ato said attended oiiice, a relayfin said unattended oiiice normally connected to said particular trunk line for response to seizure of vsaid particular trunk line in said attended office, another call responsive relay in said unattended office for said particular trunk line, means responsive to a trouble condition in said unattended ofiice for connecting said other relay to said particular trunk line in place of said normally connected relay, means rendered effective by the operation of said other relay responsive to seizure of said particular trunk line in said attended oiiice for transmitting a tone over said particular trunk line to said attended cnice to indicate the character of the trouble condition then existing in said unattended oflice, and means responsive to seizure of said trunk line by the automatic switching means in said unattended office on a call to said attended oiice while a trouble condition exists in said unattended oflice for effecting the disconnection of said other relay from said particular trunk line and the reconnection of said normally connected relay to said particular trunk line.

18. In a telephone system, an unattended office comprising subscribers lines, an attended oflice, trunklines between said ciices, automatic switching means in said unattended ofice for completing .connection between calling and called lines, a particular one of said trunk lines being used'. for the vtransmission of trouble signals from said unattended oflice to said attended office, means in said unattended office for seizing any one of said trunk lines on a call to said attended oii'ice, a relay in said unattended office normally connected to said particular trunk line for response to seizure of said particular trunk line in said attended office, another call responsive relay in said unattended office for said particular trunk line, means responsive to a trouble condition in said unattended office for connecting said other relay to said particular trunk line in place of said normally connected relay, means rendered effective by the operation of said other relay responsive'to seizure 'of said particular -trunk line by the automatic switching means in said unattended oiiice on a call to said attended oflice while a trouble condition exists in said unattended oce for effecting the disconnection ofsaid other relay from said particular trunk line and the reconnection of said normally connected relay to said particular trunk line, and means in said unattended oiiice controllable over said particular trunk line while said other relay is connected thereto for effectingithe disconnection of said other relay from said particular trunk line and the reconnection of said normally connected relay to said particular trunk line.

l19. In a telephone system,an unattended office comprising subscribers lines, an attended ofiice,z trunk lines between said offices, automatic switching means in said unattended oice for interconnecting calling and called lines, a particular one of said trunk lines being used for the transmission of trouble signals from said unattended ofce to said attended office, a trunk circuit in said unattended office normally connected to said particular trunk line, a call responsive relay in said unattended office normal-- ly disconnected from said particular trunk line, a transfer relay in said unattended oflice having normally closed contacts for connecting said particular trunk line to said trunk circuit and normally open contacts connecting said particular trunk line to said relay, a plurality of tone sources in said unattended oflice, each tone source producing a tone characterizing a different trouble condition, a plurality of trouble relays, one for each trouble condition, means responsive to a trouble condition in said unattend- ,ecl omce for operating the corresponding one of said trouble relays, the operation of any one of said trouble relays being effective to operate said transfer relay to connect said call responsive relay to said particular trunk line, means including contacts of said transfer and call responsive relays and contacts of the operated one of said trouble relays and the associated one of. said tone sources for transmitting a trouble tone over said particular trunk line to said attended omce responsive to seizure of said particular trunk line in said attended office, means controlled over said particular trunk line for causing the release of said transfer relay to disconnect said one tone source from and reconnect said particular trunk line to said trunk circuit, and means responsive to seizure of said trunk circuit by said switching means on a call to said attended office for preventing the operation of said transfer relay if a trouble condition occurs after seizure of said particular trunk line and for causing the release of said transfer relay in case said transfer relay is operated at the time of seizure of said particular trunk line by said switching means.

HARRY H. SCHNECKLOTH. 

